Making Sure the Wonder Materials Don’t Become the Wonder Pollutant
Carbon nanotubes are 10,000 times thinner than a human hair, yet
stronger than steel and more durable than diamonds. They conduct heat
and electricity with efficiency that rivals copper wires and silicon
chips, with possible uses in everything from concrete and clothes to
bicycle parts and electronics. They have been hailed as the next “wonder
material” for what could become a multi-billion dollar manufacturing
industry in the 21st century.
But as useful as nanotubes may be, the process of making them may have
unintentional and potentially harmful impacts on the environment.
MIT/WHOI graduate student Desirée Plata and her mentors—chemists Phil
Gschwend of the Massachusetts Institute of Technology and Chris Reddy
of the Woods Hole Oceanographic Institution—recently analyzed ten
commercially made carbon nanotubes to identify the chemical byproducts
of the manufacturing process and to help track them in the environment.
Plata found that the ten different carbon nanotubes had vastly
different compositions; most previous toxicity studies have generally
assumed that all nanotubes are the same. This diversity of chemical
signatures will make it harder to trace the impacts of carbon nanotubes
in the environment. In previous work (first presented last fall), Plata and colleagues
found that the process of nanotube manufacturing produced emissions of
at least 15 aromatic hydrocarbons, including four different kinds of
toxic polycyclic aromatic hydrocarbons (PAHs) similar to those found in
cigarette smoke and automobile tailpipe emissions. They also found that
the process was largely inefficient: much of the raw carbon went
unconsumed and was vented into the atmosphere.
The new research by Plata et al was published April 3 on the web site of the journal Nanotechnology.
In the next phase of Plata’s work, she will collect real-time data from
a European nanotube manufacturing facility that is poised to let her
set up the same monitors she used in the MIT lab.
“It is the indiscriminant use of poorly understood chemicals that
causes environmental and public health costs,” Plata said. “We want to
work proactively with the carbon nanotube industry to avoid repeating
environmental mistakes of the past. Instead of reacting to problems, we
hope to preclude them altogether.
Plata was honored in February for her nanotube work by the Division of
Environmental Chemistry of the American Chemical Society, which
selected her as a winner of one of its 2008 Graduate Student Paper